EP3164525B1 - Coated flat component in a cvd reactor - Google Patents

Description

The invention relates to a CVD reactor with a flat component or a flat component. The component has two preferably equally shaped, parallel and spaced apart width sides broadside, wherein an outer peripheral edge on each broad side adjacent to an edge of an outer peripheral side, an edge rounding with an edge radius of curvature and a Kantenlrundungsbogenlänge, wherein the thickness is substantially smaller than a surface area equivalent to the broadside surface diameter, wherein the component forms a core body whose material has a greater coefficient of thermal expansion than the material of a coating with which the broad sides and the peripheral side at a coating temperature which is greater than the room temperature, coated so that at room temperature the coating has a compressive stress

The WO 2013/064613 describes a CVD reactor with a gas inlet member and a susceptor arranged therein, which has a circular disk shape and carrier of substrates in a coating process.

The WO 99/43874 also describes a CVD reactor with two disk-shaped components, namely a process chamber ceiling and a susceptor for receiving the substrates to be coated in the process chamber.

The US 2005/0183669 A1 describes in the FIG. 5 a cap formed by a flat cylindrical member. The cap has a coating and two broadside facing away from each other. A broadside goes to form an edge fillet with a fillet arc length of 90 ° in a peripheral surface over. The peripheral surface merges with the formation of a bead and a kink in the second broad side.

The US 5,837,058 describes a susceptor for a CVD device in which a bead running on the edge merges to form a rounding in a peripheral surface.

The US 2003/0205324 A1 respectively US 2005/0092439 A1 describes in the FIG. 4 a susceptor with two facing away broad sides, which merge in each case to form an edge rounding in a peripheral surface. The peripheral surface has a circumferentially extending notch.

Susceptors or ceiling panels in a CVD reactor are usually made of graphite. The graphite components have a flat, disk-like shape. They have two generally identically designed, mutually parallel broadsides. It can be a cylindrical body. The thickness of the body is low compared with its diameter. In addition to components that have a circular plan, but coated flat components are used in a CVD reactor, which have a different base area than a circular base. Again, the thickness relative to a diameter is relatively small, in which case the diameter of a circle is understood to mean that has the same base area as the broad side of the component. The graphite body is coated with a few micrometers thick layer. The layer thickness of the coating is less than 1 mm. For coating usually SiC or TaC or other carbides or hard materials is used. The application of the coating takes place at temperatures of more than 1000 ° C. The core body has a larger thermal expansion coefficient than the coating, with which the broad side and the peripheral side is coated. As the coated component cools from the coating temperature down to room temperature, stresses within the coating occur. These are compressive stresses. The compressive stresses are a consequence of the different shrinkage of the layer and the core body. The shrinkage takes place in the direction of the center of gravity of the component. If it is a homogeneous body, this is the center of mass. Otherwise it is the volume center of gravity. Due to the disc shape of the component, the peripheral sides are relatively far away from the center of gravity, so that there the greatest stresses occur in the layer or in the region of the interface between the coating and the core body. Within the coating, which shrinks on cooling to a lesser extent than the core body, forms a compressive stress. High compressive stresses can influence the quality of the coating in the long term.

The invention is therefore based on the object to take measures to make the coating more robust, in particular to reduce the occurring in the coating, critical maximum stresses at any time (at any temperature) to reduce.

The object is achieved by the invention specified in the claims.

Model calculations have shown that large edge radii lead to large maximum stresses in the region of the interface between the coating and the core body. This is a consequence of the geometric stability of the arc of the coating formed by the edge rounding. The bow has a relatively high stability in the radial direction. Surprisingly, it has been found that an edge rounding with an arc length of more than 90 ° leads to a significant reduction in the maximum stress. A Significant reduction of the maximum stress also occurs when the edge radius of curvature is about 1 mm or less than 1 mm. In a preferred embodiment of a flat component in which the broad sides are designed the same, the component is thus effectively a flat cylinder, it is advantageous if the recut side on the peripheral side followed by an undercut circumferential valley. This valley can turn into a surrounding mountain. The latter can go back to a valley. The cross-sectional contour line of the peripheral side thus preferably extends undulating between the two broad sides. Since the components are coated when hot, the largest voltages occur in the cooled state, ie at room temperature. The stresses are reduced during operation, during which the component is heated to temperatures above 1000 ° C. It thus takes place at each temperature change, so with each use of the component, a load change. With the requirements of the invention, the negative influences of the frequent load changes can be reduced to the life of the component. It is advantageous if the arc length of the edge rounding is more than 90 °, preferably more than 95 °, 100 °, 105 °, 110 °, 115 or more than 120 °. The cross-sectional contour line of the peripheral side has no kinks, but has a waveform. The broad side of the component can be designed smooth. However, the broad side of the component can also have a plurality of depressions, in each case for receiving a circular disk-shaped wafer or a substrate carrier. Also, the downward-facing broad side of the component, which is a susceptor, may have a structuring. The same applies to a ceiling tile. Furthermore, it can be provided that the component has a hole. It may be a central hole of a circular cylindrical component. The inner wall of the opening also forms a circumferential side of the component, which is structured as already described above. It has rounded edges, where the radius of curvature is less than or equal to 1 mm. The wide side surface goes kink-free over the edge rounding in the peripheral side, wherein in viewing a cross-sectional area of the broad side surface corresponding straight bend-free a continuous curved arc line connects. The broad side surface is virtually smooth in a curved line, which curves without changing the direction of curvature by more than 90 ° before it turns into a curved turning point in an oppositely curved portion, which either merges into a rectilinear portion of the peripheral side or wavy continues. In a cross-sectional plane through the component, the edges of the broad side of the component run along two parallel lines. The two parallel lines correspond to the broad side surfaces and are spaced by less than half, preferably less than a quarter of their length. At their ends, these lines merge into arcuate lines associated with the edge fillets. These arc lines preferably run on circular arcs or circular arcs. The circumferential length of these sheets is greater than 90 °, preferably at least 95 ° or at least 100 °. A first end of a bow joins without kinks to each one of the parallel lines. The second end of the arch preferably merges into an oppositely curved arc section, so that at least one valley forms on the peripheral surface, the base of which springs back against the imaginary line through the vertexes of the second arches. Preferably, the component has over its entire circumference the above-described cross section of the edge region. Because of the more than 90 ° amount of arc length of the rounding creates a circumferential, at least in the edge region cross-section rounded valley between the two rounded edges of the broad side surfaces of the component. The thickness of the component is preferably at least a factor of 5, preferably a factor of 10, less than the surface-equivalent circular diameter. The component may have a circular cylindrical ground plan. But it can also have a deviating from the circular shape floor plan. The invention relates to the configuration of the peripheral edge of a coated component of a CVD reactor, wherein the component may be a susceptor, a substrate holder in a pocket of a susceptor, a ceiling plate of a process chamber or the gas outlet plate of a showerhead.

Figur 1

schematisch einen CVD-Reaktor mit darin angeordneten flachen Bauteilen 11, 12,

Figur 2

ein erstes flaches Bauteil 12 in Form eines Kreiszylinders,

Figur 3

den Schnitt gemäß der Linie 3 - 3 in Figur 2,

Figur 4

eine Darstellung gemäß Figur 3 eines zweiten Ausführungsbeispiels,

Figur 5

eine vergrößerte Darstellung gemäß Ausschnitt V in Figur 4,

Figur 6

eine Darstellung gemäß Figur 5 eines dritten Ausführungsbeispiels,

Figur 7

eine Darstellung gemäß Figur 5 eines vierten Ausführungsbeispiels,

Figur 8

ein fünftes Ausführungsbeispiel in Form einer Kreisscheibe 11 mit einem zentralen Loch 8,

Figur 9

den Schnitt gemäß der Linie IX-IX in Figur 8,

Figur 10

eine Darstellung ähnlich der Figur 1, schematisch einen CVD-Reaktor mit einem Gaseinlassorgan 13, welches eine beschichtete Gasauslassplatte 15 mit Gasaustrittsöffnungen 16 aufweist,

Figur 11

den Ausschnitt XI in Figur 10,

Figur 12

einen beschichteten Suszeptor 12 mit Taschen, in denen beschichtete Substratträger 17 angeordnet sind,

Figur 13

vergrößert den Ausschnitt XIII in Figur 12,

Figur 14

vergrößert den Ausschnitt XIV in Figur 12 und

Figur 15

ein weiteres Querschnittsprofil ähnlich der Figuren 11, 13, 14.

Embodiments are explained below with reference to the accompanying drawings. Show it:

FIG. 1

1 schematically shows a CVD reactor with flat components 11, 12,

FIG. 2

a first flat component 12 in the form of a circular cylinder,

FIG. 3

the section according to the line 3 - 3 in FIG. 2 .

FIG. 4

a representation according to FIG. 3 a second embodiment,

FIG. 5

an enlarged view according to section V in FIG. 4 .

FIG. 6

a representation according to FIG. 5 a third embodiment,

FIG. 7

a representation according to FIG. 5 a fourth embodiment,

FIG. 8

A fifth embodiment in the form of a circular disk 11 with a central hole 8,

FIG. 9

the section according to the line IX-IX in FIG. 8 .

FIG. 10

a representation similar to the FIG. 1 schematically a CVD reactor with a gas inlet member 13, which has a coated gas outlet plate 15 with gas outlet openings 16,

FIG. 11

the cutout XI in FIG. 10 .

FIG. 12

a coated susceptor 12 having pockets in which coated substrate carriers 17 are disposed,

FIG. 13

Enlarges the section XIII in FIG. 12 .

FIG. 14

Enlarges the XIV section in FIG. 12 and

FIG. 15

another cross-sectional profile similar to the Figures 11 . 13 . 14 ,

The FIG. 1 schematically shows a CVD reactor. The CVD reactor 10 has a housing in which a gas inlet member 13 is arranged, with which process gases can be fed into a process chamber of the CVD reactor 10. A process chamber ceiling 11 is formed by a graphite part having a hole in the middle. The graphite part has a circular disk-shaped outline contour.

Below the ceiling 11 of the process chamber is a bottom of the process chamber, which is formed by a susceptor 12 which can be heated from below by means of a heater 14 to a process temperature of more than 1000 ° C. The susceptor is formed by a graphite part 12 which has a has circular outline. The top of the susceptor 12 is provided with structures that form pockets for receiving substrates.

The two graphite components 11, 12 have identically designed upper sides and lower sides with regard to their outline contour. The components are schematically in the Figures 2 and 8, wherein the edge radii of curvature are shown for clarity much larger than they should be according to the invention.

That in the FIG. 2 It represents a circular disk-shaped graphite body 1 with a thickness d of 1 - 4 cm and a diameter D of more than 20 cm, in particular more than 30 cm. The entire outer surface of the graphite core body 1 is provided with a coating 2. It is a 50 to 200 μm or 75 to 150 μm thick coating of SiC or TaC. The coating is applied to the core body 1 at a temperature of more than 1000 ° C. Since silicon carbide or tantalum carbide have a lower thermal expansion than graphite, the graphite core body 1 shrinks to a greater extent along in the FIG. 3 marked and marked K in the direction of the center of gravity M as the coating 2. This has a slight bowls of the two facing away from each other, from the outline of the same designed broadsides 3 result. Also in the peripheral pages 4 a slight constriction when cooling the coated component 12 is observed.

According to the invention, the marginal edges 5 of the component 12 are provided with a slight rounding. The radius of curvature R is greater than the thickness of the coating, but not more than 1 mm.

In the in the FIGS. 4 and 5 illustrated embodiment, the peripheral edge 5 has a rounding with a radius of curvature R of 1 mm. The arc length α of the Kantenverrundung 5 is here greater than 90 °. The Kantenverrundungsbogenlänge α has a value of about 120 °. This has the consequence that the force acting vertically on the peripheral side 4, due to the shrinkage force K does not attack vertically on the surface, but at an angle to it. The force K thus splits into mutually perpendicular partial forces P and S. The force component S acting perpendicularly to the interface between the core body 1 and the coating 2 has an amount which is less than the magnitude of the force K. This leads to a reduction in the pressure forces within the coating or at the interface between the coating 2 and the core body 1.

In the area of the edge fillets 5, a compressive stress builds up within the rounded coating 2 which can not be discharged vertically into the core body 1 via the interface between the coating 2 and the core body 1. Due to the geometric stability of the sheet, the forces are rather tangentially introduced into the coating sections of the broad side 3 and the peripheral side 4. A reduction of the radius of curvature R to values below 1 mm leads to a significant reduction of these stresses.

That in the FIG. 6 illustrated embodiment shows a component with a graphite core part 1, which is provided with a silicon carbide coating. The marginal edges 5 are provided with a rounding by almost 180 °. The rounding extends beyond the plane of the broad side 3. Between the two edge roundings 5, with which the peripheral side 4 merges into the respective broad side 3, a valley 6 is formed.

In the in the FIG. 7 illustrated embodiment, the cross-sectional contour line of the peripheral side 4 is wavy, so that mountains 7 and valleys 6 alternate. Between the two edges 5, the peripheral side 4 runs without kinks. Convex rounding sections go smoothly into concave rounding sections. Thus, valleys 6 extending in the circumferential direction around the component and mountains 7 lying between valleys 6 are formed.

The FIG. 8 shows a further embodiment. Here, the component 11 is a ceiling plate. which has a hole 8 in the center. The hole 8 forms a peripheral side 4, which merges over a rounded edge 5 in the broad side 3. Here too, a valley 6 is formed between two edge fillets 5.

The invention is based on the finding that fillets should pass into the peripheral side 4 or the broad side surface 2 with the formation of constrictions, or may not be greater than a minimum value. This leads to a voltage compensation. Furthermore, it is advantageous if the individual surface sections 3, 4, 5, 6, 7 pass without kinks, ie smoothly with the formation of rounding zones with low rounding radii.

In the exemplary embodiment, graphite bodies are described which have a circular cylindrical shape. However, the invention also relates to such flat graphite bodies which have a broad-side contour which deviates from the circular shape. Again, the radius of the transition region between the broad side surface and the peripheral surface should be less than 1 mm and the radius section should be more than 90 °.

The FIG. 10 schematically shows a further embodiment of a process chamber of a CVD reactor with a gas inlet member 13, which as Showerhead is trained. It has a graphite gas outlet plate 15, the gas outlet openings 16 has. The outer peripheral surface of the gas outlet plate 15 has a cross-sectional contour, as they FIG. 11 shows. At least in the edge portion of the two opposite broad sides 3, 3 'extend the broad sides 3, 3' parallel to each other. There, the broad side surface passes in each case without kinks in a Kantenverrundung 5, which has a rounding radius R ₁ , R ₂ , which is about 1 mm. At a transition point 18, for example, after an arc length of the edge rounding 5 of 120 °, an arc section with a radius R ₃ follows without kinks. Relative to a median plane extending between the two broad sides 3, 3 ', the cross section of the edge of the gas outlet plate 15 is symmetrical. This means that the radii R ₁ , R _{2 are the} same size. At the edge rounding 5 with the radius R ₂ joins at a transition point 18 of the arc with the radius R ₃ . An imaginary straight line g, which is defined by the vertices of the edge fillets 5, spans a valley 6 whose bottom is formed by the radius R ₃ .

In the FIG. 10 The process chamber shown has a susceptor 12 which can be heated from below by means of a heating device 14. The peripheral side 4 of the susceptor 12 may have a contour as shown in the cross-sectional views of Figures 11 . 13 . 14 and 15 is shown.

The FIG. 12 shows a further embodiment of a susceptor, wherein in the pockets of the susceptor 12 substrate carrier 17 einliegen. The substrate carriers 17 are rotationally driven in the coating operation by a gas flow and are mounted on a gas bearing generated by the gas stream. The FIG. 13 shows the edge cross section of the susceptor 12 and the FIG. 14 shows the edge cross section of the substrate carrier 17. From the Figures 13 and 14 shows that the cross section of the peripheral side 4 of a series arrangement of three Arcs is composed, which arcs with the radii R ₁ , R ₂ , R ₃ transition points 18 without kinks into each other. The radii R1, R2 are about 1 mm. The radius R ₃ depends on the thickness d of the core 1, which is coated with a maximum of 0.5 mm thick coating 2 and can be substantially larger than the radii R ₁ and R ₂ . The radius R ₃ can be between 8 and 9 mm with a thickness of the component of 13 cm. The cross-sectional radius of the valley 6 between the two edge fillets 5 can thus preferably be at least five times greater than the edge radius of curvature. The radius R ₃ is further selected so that a transition point 18 is formed in which only the direction of curvature changes, but otherwise the contour lines merge into one another without kinks.

That in the FIG. 15 illustrated embodiment shows a variant in which in each case at the edge fillets 5 opposite curved arches connect with radii R3, which pass into a running on a straight valley 6, wherein the flat valley 6 kinks at transition points 19 in the hollow rounding with the radius R. ₃ passes. <B> LIST OF REFERENCES: </ b> 1 core body α arc length 2 coating d thickness 3, 3 ' broadside G Just 4 peripheral side 5 Marginal edge, edge rounding 6 valley D Circle diameter 7 mountain K force 8th hole P part forces 10 CVD reactor R1 radius 11 ceiling tile R2 radius 12 susceptor R3 radius 13 Gas inlet element S part forces 14 heater M main emphasis 15 Gas outlet plate 16 Gas outlet 17 substrate carrier 18 Checkpoint 19 Checkpoint

Claims (13)

1. A CVD reactor with a flat component (11, 12), wherein the component (11, 12, 15, 17) exhibits two broad sides (3, 3') that run parallel to each other and are spaced apart from each other by a thickness (d), wherein an outer edge (5) of each broad side (3, 3') transitions without any kinks into an edge of an outer peripheral side (4), forming an edge rounding with an edge rounding radius (R) and an edge rounding arc length (α), wherein the thickness (d) is substantially less than a circle diameter (D) that is surface-equivalent to the broad side surface, wherein the component (11, 12, 15, 17) forms a core body (1) whose material exhibits a greater coefficient of thermal expansion than the material of a coating (2) with which the broad sides (3, 3') and peripheral side (4) are coated at a coating temperature greater than the room temperature, so that the coating exhibits a compressive stress at room temperature, characterized in that the edge rounding arc length (α) is greater than 90° to reduce the stress between the coating (2) and core body (1).
2. A flat component for use in a CVD reactor, wherein the component exhibits two broad sides (3, 3') that run parallel to each other and are spaced apart from each other by a thickness (d), wherein an outer edge (5) of each broad side (3, 3') transitions without any kinks into an edge of an outer peripheral side (4), forming an edge rounding with an edge rounding radius (R) and an edge rounding arc length (α), wherein the thickness (d) is substantially less than a circle diameter (D) that is surface-equivalent to the broad side surface, wherein the component (11, 12, 15, 17) forms a core body (1) whose material exhibits a greater coefficient of thermal expansion than the material of a coating (2) with which the broad sides (3, 3') and peripheral side (4) are coated at a coating temperature greater than the room temperature, so that the coating exhibits a compressive stress at room temperature, characterized in that the edge rounding arc length (α) is greater than 90° to reduce the stress between the coating (2) and core body (1).
3. The CVD reactor according to claim 1 or component according to claim 2, characterized in that the coating is SiC, TaC or another hard material.
4. The CVD reactor or component according to one of the preceding claims, characterized in that the edge rounding radius (R) measures at most 1 mm and/or exceeds the thickness of the coating (2).
5. The CVD reactor or component according to one of the preceding claims, characterized in that the core body (1) consists of graphite.
6. The CVD reactor or component according to one of the preceding claims, characterized in that the coating (2) was applied at a temperature of >1000°C.
7. The CVD reactor or component according to one of the preceding claims, characterized in that the peripheral side (4) exhibits rounding sections that transition into each other without any kinks and form at least one valley (6).
8. The CVD reactor or component according to claim 7, characterized in that the peripheral side (4) is formed exclusively by circular arc sections in cross section.
9. The CVD reactor or component according to one of the preceding claims, characterized in that the component (11, 12) is a susceptor (12) or a cover plate (11), a substrate carrier (17) or a gas outlet plate (15) of a gas inlet member (13).
10. The CVD reactor or component according to one of the preceding claims, characterized in that the component (11, 12) exhibits a circle cylindrical shape, and in particular exhibits a diameter (D) of at least 20 cm, in particular at least 30 cm, and a thickness (d) of between 1 and 3 cm.
11. The CVD reactor or component according to one of claims 1 to 9, characterized in that the component (11, 12) exhibits an outline that deviates from the circular shape.
12. The CVD reactor or component according to one of the preceding claims, characterized in that, in a cross sectional plane through the component (11, 12, 15, 17), the cross section of the component exhibits two lines running parallel to each other at least near the edge of the component, which correspond to the edge regions of the broad sides (3, 3') of the component (11, 12, 15, 17), and the ends of these lines transition without any kinks into arc lines, which correspond to edge roundings (5), wherein the arc lines run on a circular arc or near-circular arc, and a curved connecting line joins the arc lines with each other without any kinks, and forms at least one valley (6), which jumps back relative to a straight line drawn through the vertices of the arc lines.
13. The CVD reactor or component according to one of the preceding claims, characterized in that the peripheral side (4) is formed in cross section exclusively by circular arc lines with radii (R1, R2, R3) that are arranged one behind the other.

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